1. Field of the Invention
The present invention relates generally to an asynchronous transfer mode (hereinafter referred to as ATM) protection triggering method for determining a failure generation location in an ATM network wherein the protected domains are sequentially set or nested. More particularly, it relates to an ATM protection triggering method using xe2x80x9creceived-AIS (alarm indication signal)xe2x80x9d flag, which determines whether the failure is generated within the protected domain or not.
2. Description of the Related Art
An ATM protection triggering method belongs to an ATM protection switch field. A standardization regarding this ATM protection triggering method has been progressed in the ITU-T SG13. A protection switch function can be set by each ATM interface unit. Any protected domain may include another protected domain, and may have a nested structure included in other protected domain. The protected domain can be extended to an entire area between the originating user and the answering user, or can be set in one portion among the entire area. The reason why the protected domain is established is to prepare a spare link for replacing a defective link when a failure occurs in a link within a protected domain therein, thereby enhancing a restoration ability and a reliability of the ATM network. The greatest problem among the present protection switch functions is a method for determining whether a failure is generated within the protected domain or not.
Conventionally, in order to determine whether the failure generation position is present in the protected domain or is out of the protected domain in a nested structure of the protected domain, a new field should be added to an end-to-end alarm indication signal (AIS) cell.
However, the method for adding new field to the end-to-end AIS cell requires a modification of the end-to-end AIS cell at both a source point and a sink point of the protected domain. Accordingly, a shortcoming that CRC(Cyclic Redundancy Check)-10 should be calculated in a real-time, and a backward compatibility that an original end-to-end operation and maintenance (OAM) cell should be changed are generated in the conventional method.
The present invention is directed to an ATM protection triggering method using xe2x80x9creceived-AISxe2x80x9d flag which substantially obviates the above-described problem due to limitations and disadvantages of the related art.
It is an object of the present invention to provide an ATM protection triggering method using xe2x80x9creceived-AISxe2x80x9d flag, which determines whether the failure is generated within a protected domain or not.
It is another object of the present invention to provide an ATM protection triggering method using xe2x80x9creceived-AISxe2x80x9d flag, which determines whether a failure is generated within a protected domain or not, by determining whether the xe2x80x9creceived-AISxe2x80x9d flag is xe2x80x9c0xe2x80x9d in case that a node detecting a failure link transmits an end-to-end AIS cell to a downstream side node, and a source point passing the end-to-end AIS cell sets the xe2x80x9creceived-AISxe2x80x9d flag to xe2x80x9c1xe2x80x9d and then receives xe2x80x9cAIS cell receivingxe2x80x9d signal from a sink point of the protected domain, thereby obviating a CRC-10 calculation problem and a backward compatibility.
In order to realize the above objectives, in an asynchronous transfer mode (ATM) protection triggering method for determining a failure generation position in an ATM network wherein protected domains are sequentially set or nested, the ATM protection triggering method using xe2x80x9creceived-AISxe2x80x9d flag includes:
a first step in which xe2x80x9creceived AISxe2x80x9d flag of a source point of the protected domain is initialized as xe2x80x9c0xe2x80x9d at every protected domain;
a second step in which a node detecting a failure generates an end-to-end AIS cell to a downstream side node;
a third step in which a source point of a protected domain passing the end-to-end AIS cell of the second step performs xe2x80x9creceived-AISxe2x80x9d flag processing;
a fourth step in which a sink point of the protected domain receiving the end-to-end AIS cell of the second step performs the end-to-end AIS cell processing, and send an AIS cell receiving report to the source point of the protected domain; and
a fifth step in which the source point of the protected domain receives the AIS cell receiving report of the fourth step, and then a protection switch is operated.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objective and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.